GMAT Prepositions and Idioms: On

UPDATE: You can find this blog and others about idioms in our new GMAT Idiom eBook!

Prepositions in English display a powerful diversity of uses. Your preposition knowledge will most certainly be tested in the GMAT. In previous preposition article, we talked about the proposition “against”.  Here, we will look, at the preposition “on”.


Prepositions on the GMAT

A preposition must be followed by a noun — or by something playing the role of a noun.   This latter category includes gerunds and substantive clauses.

1) The CEO refused to expend any more capital on saving the failing divisions.

2) Washington well understood that his long-term success in the War of American Independence might well depend on whether Franklin would be able to persuade the French to join as allies.

In sentence #1, the object of the preposition “on” is a gerund phrase, and in sentence #2, the object is a substantive clause.   Incidentally, both of these are exemplary of idioms involving these prepositions.


The Preposition “On”

The preposition “on” literally denotes the surface supporting something (“the book is on the table”), and metaphorically, it can refer to a circumstance or the topic of a talk.

3) On formal occasions, the general wore his ceremonial saber.

4) An acknowledged authority on eighteenth century literature, the professor was asked to lead a seminar on post-modern poetry.

The three most important idioms involving “on” are

based on

expend (time/money/energy) on

depends on (whether)


Idiom: “Based on”

First of all, the idiom P is based on Q means would literally mean that Q is the physical foundation on which P sits.  This idiom is rarely used in its strictly literal sense.  More often, Q is the evidence or philosophical underpinning that supports P.

5) The schema of punishments described in Dante‘s Inferno is based on the theology of Thomas Aquinas.

Similarly, the idiom based on Q, P is a perfectly valid participial modifier construction.   Again, Q is the thing doing the supporting, and P is the thing supported.

6) The doctor’s hunch, based on 25 years of research in the field, was that the new medicine would be successful.

Here, the participial phrase “based on 25 years of research in the field” modifies the noun it touches, the noun “hunch” — the doctor’s hunch is supported by his many years of research.   This is perfectly correct.

This idiom, though, is wantonly abused in colloquial speech.


Both of these might be said colloquially, both are 100% WRONG.  In #7, the team is not supported by its losing record last year — it would be far more accurate to say something like “Because the team had a losing record last year, we suspect that ….”   The authoritarian speaker of #8 is certain not supported by his interlocutor’s bad behavior.  Again, a “because” clause would be far more accurate.


Idiom: “Expend … on”

The verb “to expend” means, in essence, the same thing as the verb “to spend.”  When we spend or expend, we are giving away a resource (money, time, energy, etc.) and thereby acquiring some good.  In the idiom to expend P on Q, P is the “price”, the resource spent in this interaction, and Q is the good “purchased” with this expenditure.  The noun form of this same idiom is the expenditure of P on Q.  (For more on verb-forms vs. noun-forms, see this post.)

9) The United States has expended over eight-hundred billion dollars on the post-9/11 War in Iraq.

10) Having already won a Nobel Prize and garnered international fame, Einstein expended the last three decades of his life on an apparently fruitless search for a Unified Field Theory.

11) In the late rounds of a match, a skilled boxer will be parsimonious with powerful punches, preferring not to expend valuable energy on blows that don’t substantially damage his opponent.


Idiom: “Depends on”

If P depends on Q, then Q is the condition or circumstance that either will allow P to happen or will affect the quality of P.   In other words, knowing Q will answer some vitally important question about P.

12) The location of their wedding reception will depend on the weather.

13) A baseball player’s hitting prowess depends more on his visual abilities than on anything else.

In more complex sentences, either P or Q — or both! — from this structure could be a substantive clause, most typically beginning with the word “whether.”

14) Lincoln felt that issuing the Emancipation Proclamation should depend on whether the Army of the Potomac would be able to drive the Confederate forces out of Maryland.

15) Whether any individual particle decay sequence occurs depends on whether all relevant conversation laws permit it.

16) How easily a name is remembered does not depend on the qualities of that person.

17) What a person fundamentally believes depends surprisingly little on how much that person has in her bank account.

18) How soundly a person sleeps on any given night depends on what that person eats in the hours immediately before retiring.

Substantive clauses galore!  This idiom lends itself well to them.



Know the idioms given in bold in this post.  As always with idioms, read, read, read!   Search for the idioms in this post in context.  You understand English best when you understand it in context.


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  • Mike MᶜGarry

    Mike served as a GMAT Expert at Magoosh, helping create hundreds of lesson videos and practice questions to help guide GMAT students to success. He was also featured as "member of the month" for over two years at GMAT Club. Mike holds an A.B. in Physics (graduating magna cum laude) and an M.T.S. in Religions of the World, both from Harvard. Beyond standardized testing, Mike has over 20 years of both private and public high school teaching experience specializing in math and physics. In his free time, Mike likes smashing foosballs into orbit, and despite having no obvious cranial deficiency, he insists on rooting for the NY Mets. Learn more about the GMAT through Mike's Youtube video explanations and resources like What is a Good GMAT Score? and the GMAT Diagnostic Test.